Usually when I hear talk of embedded passives, the subject is concerning resistors and capacitors created by essentially laying down specialized layers of a specific metal or resistive compound connected to traces in an inner layer.
I ran across this silicon part from TI that's designed to be embedded into PCBs (TPD2E007YFMRG4). Actually, it can be both embedded or placed on top like a miniature BGA. It's a 0.8mm x 0.8mm chip scale part with four 0.4mm pitch bumps. The package height is only 0.15mm so I'd call that pretty thin. It's a two channel ESD protector with a breakdown voltage of 14V, protecting up to 15Kv.
Trying to take these pictures was interesting. That's a paperclip next to them, by the way. Every time I'd get them lined up the way I wanted them, I'd bump them or breath wrong or something.
Now all I have to do is figure out how to get the little things back in the cut strip. Or maybe I'll just brush them on to the floor and they'll blend into the carpet.
Don't despair, it's still 800 times bigger then the Proteus